Malmström, Eva

Abstract [en]

In the past years, a growing concern for the environment has forced the research to focus more on new “greener” materials. The most abundant organic raw material in the world is cellulose. This, in combination with the versatility of the material, makes it interesting as a green option in various applications. However, to be able to take advantage of all characteristics possessed by cellulose, i.e., use it in applications where it is not inherently compatible, modification is often necessary.1-3 One common method used for modifying cellulose is grafting of polymers onto/from the cellulose chain. This offers a way of changing the inherent properties of cellulose to attain new properties, such as dimensional stability and water repellency.3

Additionally, it has been shown that polyectrolytes can be physiosorbed onto charged surfaces.4 This has made it possible to physically modify cellulose by adsorbing a polymer through electrostatic interactions instead of attaching it with a covalent bond.5 However, a more detailed investigation concerning the differences, such as surface coverage and grafting/physiosorption efficiency, between a covalent and physical attachment of a polymer has to the author’s best knowledge earlier not been performed. Therefore, this project aims to compare these two techniques. A block copolymer consisting of poly(ε-caprolactone) (PCL) and poly(di(methylamino)ethyl methacrylate) (PDMAEMA) is made, see figure 1 for 1H-NMR-spectrum.

Figure 1. The 1H-NMR-spectrum of PCL-block-PDMAEMA (in CDCl3).

The PDMAEMA-part is then quaternized (figure 2), which results in a charged chain – a polyelectrolyte.

Further work after preparation of fibres may include such steps as making of fiber-reinforced composites, out of both chemically and physically modified fibres, where for example differences concerning mechanical properties would be investigated.